Rhizomatous and sod-forming, to 10 or even 15 dm, not stoloniferous; larger (upper) ligules mostly 2.5-6 mm, higher than wide; lvs 3-8 mm wide; panicle 10-20 cm, notably suffused with purplish-red, at anthesis triangular-ovoid, with widely spreading, unequal branches, sometimes later more contracted; at least some of the panicle-branches floriferous to the base; panicle- branches and often even the pedicels scabrous; spikelets rather crowded, 2-3.5 mm; glumes scabrous along the keel; lemma two-thirds as long as the glumes, distally scabrous, awnless or seldom with a short dorsal awn; callus minutely bearded; palea half to two-thirds as long as the lemma; anthers 0.8-1.5 mm; 2n=42. Native of Europe, cult. and escaped into moist meadows, shores, coastal marshes, and other moist places throughout most of the U.S. and s. Can. (A. alba, misapplied; A. stolonifera var. major)

This species has been commonly sown as a pasture and hay grass in all parts of the state, especially in the southern part. It has abundantly escaped everywhere and is found along roadsides and railroads and in fallow fields, pastures, and waste places. Besides the commercial redtop, seed of other species of the bentgrasses have been imported and sown in lawns and on golf courses. Several strains of each species have been developed and some European authors credit one species with 15 varieties and subvarieties. The species are separated with difficulty and the task is complicated by the addition of the many cultivated forms.

FNA 2007, USDA FEIS, Heil et al. 2013, Tilley et al 2010.

Common Name: redtop Duration: Perennial Nativity: Non-Native Lifeform: Graminoid General: Introduced perennial grass with rhizomes to 25 cm, erect stems 20-120 cm, sometimes geniculate at base, sometimes rooting at lower nodes, 4-7 nodes per culm. Vegetative: Leaves mostly cauline, sheaths smooth or sparsely minutely roughened, ligules longer than wide, dorsal surfaces usually scabrous, sometimes smooth, apices rounded to truncate, basal ligules 1-4.5 mm, upper ligules 2-7 mm; blades 4-10 cm long, 3-8 mm wide, Inflorescence: Panicles 8-25 cm long, less than half length of stem, 3-15 cm wide, erect open, ovate, lowest node with 3-8 branches; branches scabrous, spreading during and after anthesis, lower branches 4-9 cm, usually with many shorter secondary branches, resulting in crowding of spikelets; on pedicels 0.5-3.5 mm; spikelets narrowly ovate to lanceolate, green and slightly to strongly suffused with purple; glumes subequal, 1.5-3 mm, lanceolate, 1-veined, acute to apiculate, lower glumes scabrous on distal half of midvein, upper scabriculous on distal half of midvein; sparse callus hairs to 0.5 mm; lemmas 1.5-2.5 mm, 3-5 veined, veins obscure, usually unawned, but when awned, 0.5-1.5 mm straight awn. Ecology: Widespread and considered a serious weed, growing in fields, roads, ditches, other disturbed habitats. In the Southwest it grows above 5,000 ft (1524 m); flowers June to October. Distribution: Native to Europe and north Africa; naturalized throughout the US and Canada. Notes: Often confused with A. stolonifera, and sometimes treated as a variety of that species. A. gigantea has a panicle which remains open, while A. stolonifera-s panicle contracts after anthesis. Additionally, A. stolonifera has elongated leafy stolons which root at the nodes, and occasionally has short rhizomes. A. gigantea has no stolons but does have well-developed rhizomes. Can look like each other without inflorescences, so pay attention to the plant being rhizomatous or stoloniferous. A. gigantea is a preferred nesting habitat for prairie chickens, as their native prairie is now so scarce. The species was a commonly grown pasture grass throughout the US before 1940, and the NRCS continues to recommend its use for erosion control and as a pasture and turf grass. Ethnobotany: Unknown Etymology: Agrostis is from the Latin and Greek names for a type of grass, from Greek agron or agros, field or pasture, while gigantea means gigantic. Synonyms: Agrostis alba, Agrostis gigantea var. dispara, Agrostis nigra, Agrostis stolonifera subsp. gigantea, Agrostis stolonifera var. major Editor: SBuckley, 2010, AHazelton 2015